Leaving any material on the top case (keyboard and palm rest area) could result in damage to the display when you close it. ... Do not use palm rest covers or keycap covers, as the additional thickness may interfere with the designed closed position of the display.

Is it safe to put keyboard cover?

As the technician pointed out, a keyboard cover can give people false assurance that their keyboard is safe from major spills when in reality, it is only covering a single part of the laptop. Remember that the protection is limited, especially if you knock over a big glass of lemonade while typing.

Do silicone keyboard covers damage screen?

Yes, a keyboard cover can damage the display.